I doubt that's legally decided yet. There hasn't been precedent as it hasn't been challenged yet.

I mean Claude will tell you because anthropic made it tell you that, doesn't mean it's true.

GoFundMe and indigogo aren't responsible for the actions of the funded projects either, hence it's unlikely that any judge would decide that the liability would go to the platform if it can show it's doing it's best effort in moderation wrt illegal content

If you mean just throw it together and then don't moderate at all then .. yeah, you'll be held liable. But that's not because of the person paying the prompt, it's because moderating illegal content is the responsibility of the platform provider.